1. Success of a repeated tined lead trial in a refractory OAB population
Tomas L. Griebling, University of Kansas, Kansas City, KS
Karen Noblett, University of California, Riverside, CA, Jeffrey Mangel, MetroHealth Medical Center, Cleveland, OH, Jason Bennett, Female Pelvic Medicine, Grand Rapids, MI, Craig Comiter, Stanford University, Stanford, CA, Erin Bird, Scott and White Healthcare, Temple, TX, Suzette E. Sutherland, University of Washington, Seattle, WA, Kellie Chase Berg, Medtronic, Minneapolis, MN, Fangyu Kan, Medtronic, Minneapolis, MN, Steven Siegel, Metro Urology, Woodbury, MN
Objective
To determine the success of a repeat therapy evaluation for sacral neuromodulation after initial test stimulation failure and evaluate long term efficacy.
Background
Study Design and Methods
The International Continence Society (ICS) Guidelines recommend sacral neuromodulation (SNM) as specialized treatment for idiopathic overactive bladder (OAB). SNM provides a means to interact with the neural system that controls effector organs and muscles innervated by the sacral nerves in the pelvic region. The InterStim® system provides SNM through an implantable neurostimulator that delivers electrical stimulation via a lead placed close to the sacral nerves.
InSite is an ongoing, prospective, multicenter post-approval study. Subjects with bothersome symptoms of overactive bladder (OAB) including urinary urge incontinence (UI) or urgency-frequency (UF), who had not exhausted all medication options (failed at least 1 anticholinergic medication and had at least 1 medication not tried) were included.
Subjects completed test stimulation with a tined lead and external neurostimulator for 14 days.
Therapeutic success was defined as a UI or UF response; for UI as a ≥ 50% improvement in average leaks/day, for UF as a ≥ 50% improvement in voids/day or a return to normal voiding frequency (<8 voids/day) on a 3-day consecutive voiding diary.
Subjects not meeting success were allowed to repeat test stimulation with a new lead implant at the discretion of the investigator. Those subjects meeting the definition of therapy success went on to receive an implantable neurostimulator.
Therapy efficacy was collected using electronic voiding diaries. Quality of life was evaluated using the validated disease-specific International Consultation on Incontinence Modular Questionnaire (ICIQ-OABqol).
Results
Baseline Demographics
Subjects with repeat test stimulation
(n=29)
Gender, female
90%
Mean age at implant (years)
59 ± 12.8
Mean duration of diagnosis at implant (years)
10.2 ± 9.4
OAB Qualification per diary*
17% UI only
34% UF only
45% both UI and UF
Baseline leaks/day
4.0 ± 2.4 (n=18)
Baseline voids/day
14.4 ± 5.3 (n=23)
Median # of OAB medications tried prior to implant 2
Overall, 340 subjects underwent test stimulation with 272 (80%) going on to full device implant. Of the 68 subjects who failed the initial trial, 29 received an additional tined lead to undergo repeat test stimulation.
Reasons for initial test stimulation failure in these 29 subjects were:
22 had not met therapy success criteria (9 were later implanted with the neurostimulator after repeat test stimulation, while 13 were not)
5 had the lead replaced due to adverse events
1 had the lead replaced due to an adverse event and technical observation
1 was due to insufficient completion of the voiding diary
*Baseline qualification not available for 1 subject
Of these 29 subjects, 16 (55%) went on to receive a full system implant. The OAB therapeutic success rate was 86% at 1 year (n=12), 75% at 2 years (n=9), and 82% (n=9) at 3 years post-implant which is similar to the larger all implanted cohort1.
There were statistically significant improvements compared to baseline in Health Related QOL score at 1-year, 2-year and 3-years as displayed in the Figure.
Twelve device-related adverse events occurred in 6 subjects post full system implant through 3 years of follow-up:
3 events of undesirable change in stimulation
2 events of therapeutic product ineffective
1 event of each in 7 other adverse event types
Health Related QOL Score
Years post full system implant
*p<0.05, **p<0.01, ***p<0.001, Error bars are 95% confidence intervals
MID: is the smallest score change that is perceived beneficial to patients and is often used to determine whether changes in scores are considered clinically significant. The MID for the OABqol subscales has been suggested to be 10 points.  
Conclusion
These results demonstrate that over 50% of patients who do not initially respond to a staged tined-lead trial may respond to repeat test stimulation. The long term subjective and objective improvements are similar to the larger cohort of implanted subjects in the trial.
1Siegel, et al. Three-year follow-up results of a prospective, multicenter study in overactive bladder subjects treated with sacral neuromodulation. Urology 2016.
This trial was sponsored by Medtronic, Inc.